Segmentation, condensation and bilateral symmetry of the nuclei of polymorphonuclear leukocytes seem related to their function. Segmentation of the nuclei into two or more lobes and their condensation facilitate their passage (diapedesis) through the endothelial layer of blood vessels to the extravasal space and subsequent locomotion through the interstitial compartment of different tissues. Bilateral symmetry of these nuclei along with their association to the cytoskeletal fibers contribute to their efficiency in locomotion by alignment of the axis of nuclear symmetry to the axis of cellular polarity, which orients towards the direction of locomotion in response to cytokines and other stimuli. Observations of the cytogenetic facets of intranuclear order support these assumptions.

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BackgroundOne fundamental finding of the last decade is that, besides the primary DNA sequence information there are several epigenetic “information-layers” like DNA-and histone modifications, chromatin packaging and, last but not least, the position of genes in the nucleus.ResultsWe postulate that the functional genomic architecture is not restricted to the interphase of the cell cycle but can also be observed in the metaphase stage, when chromosomes are most condensed and microscopically visible. If so, it offers the unique opportunity to directly analyze the functional aspects of genomic architecture in different cells, species and diseases. Another aspect not directly accessible by molecular techniques is the genome merged from two different haploid parental genomes represented by the homologous chromosome sets. Our results show that there is not only a well-known and defined nuclear architecture in interphase but also in metaphase leading to a bilateral organization of the two haploid sets of chromosomes. Moreover, evidence is provided for the parental origin of the haploid grouping.ConclusionsFrom our findings we postulate an additional epigenetic information layer within the genome including the organization of homologous chromosomes and their parental origin which may now substantially change the landscape of genetics.Electronic supplementary materialThe online version of this article (doi:10.1186/s13039-016-0243-y) contains supplementary material, which is available to authorized users.

An improved method for human sperm chromosome preparation is described. Improvements include 1) the use of a sperm population with high motility and normal morphology for insemination, 2) the insemination and postinsemination culture of zona-free eggs in Holmes medium, which does not require serum supplementation, 3) control of sperm concentration at insemination to avoid heavy polyspermy, 4) reduction of the occurrence of egg agglutination by placing the medium for postinsemination culture in a ring or crescent shape instead of a droplet, and 5 ) application of a two-step fixation method to augment the efficiency of chromosome preparation.